The present invention relates to a system for transmitting the power of an engine to four driving wheels of a four-wheel drive vehicle.
In a conventional four-wheel drive vehicle having a central differential, which is called a full time four-wheel drive vehicle, the central differential operates to uniformly distribute the torque of an engine to front wheels and to rear wheels of the vehicle.
It is known that the distribution ratio of torque influences driveability, steerability, stability, starting characteristic and other factors. Namely, when the distribution to the front wheel is increased, a stable cornering characteristic at high vehicle speed is established, and when the distribution to the rear wheels is increased, steerability at low vehicle speed is improved. In the conventional four-wheel drive vehicle, the distribution ratio of torque to the front wheels and to the rear wheels can not be changed.